1. Field of the Invention
The present invention relates to a carbon-fiber reinforced thermoplastic resin (hereinafter referred to as CFRTP), to a carbon fiber for use in the CFRTP as a reinforcing material, to a thermoplastic resin for use in the CFRTP as a matrix, and to a prepreg (preimpregnated material) for use in producing the CFRTP. A carbodiimide agent is employed in the present invention in order to enhance adhesion between the carbon fiber and the thermoplastic resin.
2. Description of the Prior Art
For production of CFRTPs, there are known methods for improving adhesion between a carbon fiber which is a component as a reinforcing material and a thermoplastic resin which is a matrix component. Such methods include, for example: coating the surface of the carbon fiber with polyvinylpyrrolidone (disclosed by Japanese Patent Application First Publication No. Sho 57-56586); coating the surface of the carbon fiber with polyurethane resin (disclosed by Japanese Patent Application First Publication No. Sho 58-126375); coating the surface of the carbon fiber with acrylonitrile-styrene copolymer resin (disclosed by Japanese Patent Application First Publication No. Sho 59-71478); sizing the surface of the carbon fiber with polyetherimide resin (disclosed by Japanese Patent Application First Publication No, Sho 62-299580).
However, the excellent mechanical properties of the carbon fiber have not been satisfactorily exploited in the CFRTPs, as the improvement in adhesion between the carbon fiber and the thermoplastic resin as the matrix was not sufficient according to the prior methods, and therefore, mechanical strength of these CFRTPs was inferior compared to that of carbon-fiber reinforced plastics (CFRPs) which use thermosetting resin as a matrix.